Calibrating Neve 2254E Set +8

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I am in the process of calibrating a pair of Neve 32254E Limiter/Compressors
and using tones I appear to have them where I want them. However,
there is one calibration on them that I don't know what to do with.
It is labelled "Set +8". I understand that broadcast often uses +8
as a standard as opposed to +4 dBU. However, these are variable
pots so it isn't as if I can "click" them in and out of a higher
operating range. Anyone know what these do?

The other calibrations are "PPM in", "PPM out", "set gain", and "set
threshold", BTW. But these all make sense to me. However, I do
seem to remember that the "PPM" designation is related to +8
broadcast standard.

Related question---I had a rack made for these. While it is pretty
nicely made, they appear to have ignored my request for a larger
power supply. These modules need 250 mA. People like Fletcher and
Geoff Tanner have stated that you need 6 to 10 times that capacity
to operate them optimally meaning I need something in the range of
3 to 5 amps (at 24VDC, not that it matters). The power supply they
installed is only rated at 1.2 amps. I am thinking about ordering
a beefier power supply and putting it in myself. But in the meantime
can I not just avoid saturation/clipping (unless that's
what I want!) by just staying off the makeup gain and compensating
for it on my mixer?

BTW, they sound really good, except for being kind of noisy.

Thanks,

Rob R.
 
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In article <cvaltl$4ta$1@news1.chem.utoronto.ca> reedijk@hera.med.utoronto.ca writes:

> I am in the process of calibrating a pair of Neve 32254E Limiter/Compressors
> and using tones I appear to have them where I want them. However,
> there is one calibration on them that I don't know what to do with.
> It is labelled "Set +8". I understand that broadcast often uses +8
> as a standard as opposed to +4 dBU. However, these are variable
> pots so it isn't as if I can "click" them in and out of a higher
> operating range. Anyone know what these do?

I suspect that they're for meter calibration. Is there a switch to
select between +4 and +8 dBu nominal operating level? If so, switch it
to +8, put in a tone at +8 dBu, switch the meter to read input, and
adjust the pot so the meter reads 0.

> The other calibrations are "PPM in", "PPM out", "set gain", and "set
> threshold", BTW. But these all make sense to me. However, I do
> seem to remember that the "PPM" designation is related to +8
> broadcast standard.

That may have something to do with it. I guess you really need answer
from someone who knows that limiter or at least has the documentation.
But there doesn't necessarily have to be a relation. Some studios just
operated at +8 dBu nominal, and you always want to read 0 VU at
nominal level, whatever your choice for that happens to be.


--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
 
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"Rob Reedijk" <reedijk@hera.med.utoronto.ca> wrote in message
news:cvaltl$4ta$1@news1.chem.utoronto.ca...
>I am in the process of calibrating a pair of Neve 32254E
>Limiter/Compressors
> and using tones I appear to have them where I want them. However,
> there is one calibration on them that I don't know what to do with.
> It is labelled "Set +8". I understand that broadcast often uses +8
> as a standard as opposed to +4 dBU. However, these are variable
> pots so it isn't as if I can "click" them in and out of a higher
> operating range. Anyone know what these do?
>
> The other calibrations are "PPM in", "PPM out", "set gain", and "set
> threshold", BTW. But these all make sense to me. However, I do
> seem to remember that the "PPM" designation is related to +8
> broadcast standard.
>
> Related question---I had a rack made for these. While it is pretty
> nicely made, they appear to have ignored my request for a larger
> power supply. These modules need 250 mA. People like Fletcher and
> Geoff Tanner have stated that you need 6 to 10 times that capacity
> to operate them optimally meaning I need something in the range of
> 3 to 5 amps (at 24VDC, not that it matters). The power supply they
> installed is only rated at 1.2 amps. I am thinking about ordering
> a beefier power supply and putting it in myself. But in the meantime
> can I not just avoid saturation/clipping (unless that's
> what I want!) by just staying off the makeup gain and compensating
> for it on my mixer?
>
> BTW, they sound really good, except for being kind of noisy.
>
> Thanks,

Rob
In the UK and wherever else they are used, PPM scales go from 1 to 7 in
increments of 4dB, where "ppm1" is just about -12 or -14dB below 0 ref ("ppm
4"), and peak level (+8dB above 0 ref) is equal to "ppm 6" - all read at
steady tone state. The dynamic range between electrical Zero (no signal) and
1 is often immaterial.
After adjusting Set Gain and Threshold (BTW, this could be an L/C function)
where 0.775V rms gives peak 4, inject a new level of 1.95V rms, adjust Set
+8 to give peak 6. You may have to juggle between Set Gain and Set +8 to get
a happy compromise.
Because of a law network within PPM amps, certain sections switch in only
when a progressively higher level is detected. If you have 2 PPMs side by
side, ensure that when fed in dual mono mode, your line-up makes the attack
and the decay are visually synchronous.
Don't worry about the available PSU current, the devices are only basically
2 processors, 2 line output drivers and a 1mA meter driver or two per
channel.
Good stuff, Neve! Tried to get the manual from AMS Neve?
http://www.ams-neve.com/cont.htm
Jim
>
> Rob R.
 
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Rob
My error, now I have re-read your intro, I see you don't have an integral
PPM, but the facility for it.
But have you got the panel-mounted Stereo Separate/Link Switch fitted
between these two modules?
Essential to "link" them to maintain the average centre image, not pulling
too much to one side when influenced and controlled by left or right
programme dynamics.

Jim
 
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Rob Reedijk <reedijk@hera.med.utoronto.ca> wrote:
> I am in the process of calibrating a pair of Neve 32254E Limiter/Compressors
> and using tones I appear to have them where I want them. However,
> there is one calibration on them that I don't know what to do with.
> It is labelled "Set +8". I understand that broadcast often uses +8
> as a standard as opposed to +4 dBU. However, these are variable
> pots so it isn't as if I can "click" them in and out of a higher
> operating range. Anyone know what these do?

Geoff Tanner sent me an email and I can now tell you that "set +8" is
a calibration for the limiter. Basically, crank a very high level tone
into the unit, set the limiter to +8, and adjust this setting until the
output reads +8.

I will post my steps for calibrating 2254Es in the next day, once I have
confirmed proper operation.

Rob R.
 

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